Vehicle antenna device

Abstract

A vehicle antenna device according to the present invention comprises: a dielectric substrate; an antenna that is disposed on a first main surface side of the dielectric substrate; an antenna conductor that is connected to the antenna and disposed on the first main surface side; a conductive film that is disposed on the dielectric substrate on a second main surface side on the reverse side from the first main surface side and has a porous region in the interior thereof in a plan view of the dielectric substrate; a signal electrode that is disposed further inward on the second main surface side than the outer edge of the porous region in a plan view of the dielectric substrate and is electrically connected to the antenna conductor; and a ground electrode that is electrically connected to the conductive film in a plan view of the dielectric substrate.

Description

[Technical Field]

[0001] The present invention relates to a vehicle antenna device. This application claims priority based on Japanese Patent Application No. 2021-150081, filed on September 15, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] In recent years, antennas that are installed on the roof of a vehicle have become known, such as roof antennas (so-called shark fin antennas) that use a protruding cover on the roof of the vehicle to store various antenna elements within the cover. Some vehicle models also use roof glass with an opening in the roof. For vehicles that use roof glass in this way, a protruding antenna attached to the roof glass is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japan Special Publication No. 2010-510954 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, vehicle glass is known in which a conductive film, such as a heat ray reflective film or a Low-E (Low Emissivity) coating, is provided on the glass surface. Such vehicle glass with a conductive film on the glass surface prevents radio waves from propagating from outside the vehicle into the interior of the vehicle. Therefore, for example, in the case of roof glass provided with a conductive film, an antenna device is required that minimizes mechanical processing of the glass itself and provides a stable gain in order to connect the glass to electronic components located inside the vehicle that process radio wave signals received by a protruding antenna.

[0005] The present invention provides a vehicle antenna device that can obtain a stable gain with minimal mechanical processing of the glass itself. [Means for solving the problem]

[0006] A vehicle antenna device according to one embodiment of the present invention includes a dielectric substrate, an antenna arranged on a first main surface side of the dielectric substrate, an antenna conductor connected to the antenna and arranged on the first main surface side, a conductive film arranged on a second main surface side of the dielectric substrate opposite the first main surface side and having a hole region therein in a planar view of the dielectric substrate, a signal electrode arranged on the second main surface side of the dielectric substrate inside an outer edge of the hole region in a planar view of the dielectric substrate and electrically connected to the antenna conductor, and a ground electrode electrically connected to the conductive film in a planar view of the dielectric substrate.

[0007] In the vehicle antenna device according to one aspect of the present invention, the antenna conductor and the signal electrode may be electrically connected by capacitive coupling.

[0008] In the vehicle antenna device according to one aspect of the present invention, the antenna conductor and the signal electrode may be directly connected to each other by a connection conductor disposed in a through hole of the dielectric substrate.

[0009] In one embodiment of the present invention, the dielectric substrate is a first dielectric substrate, and includes a second dielectric substrate facing the second main surface of the first dielectric substrate and arranged parallel to the second main surface, and an intermediate film arranged between the first dielectric substrate and the second dielectric substrate, the second dielectric substrate having a third main surface facing the first dielectric substrate and a fourth main surface opposite to the third main surface side, the conductive film being arranged between the first dielectric substrate and the second dielectric substrate, and the signal electrode and the ground electrode being arranged on the fourth main surface side.

[0010] In the vehicle antenna device according to the aspect of the present invention, the conductive film may be disposed in contact with the second main surface.

[0011] In one embodiment of the present invention, the intermediate film may include a first intermediate film and a second intermediate film, and the conductive film may be sandwiched between the first intermediate film and the second intermediate film.

[0012] In the vehicle antenna device according to one aspect of the present invention, the conductive film may be a light control film including a conductor.

[0013] In the vehicle antenna device according to the aspect of the present invention, the conductive film may be disposed in contact with the third principal surface or the fourth principal surface.

[0014] In a vehicle antenna device according to one embodiment of the present invention, the intermediate film includes a first intermediate film and a second intermediate film, the conductive film includes a first conductive film and a second conductive film, the first conductive film and the second conductive film are arranged at two of the following positions: a position on the second main surface, a position between the first intermediate film and the second intermediate film, a position on the third main surface, and a position on the fourth main surface, and are arranged in order from closest to the first dielectric substrate, and the second conductive film may have a second hole region that is arranged to overlap with a first hole region, which is the hole region of the first conductive film, in a planar view of the first dielectric substrate.

[0015] In one embodiment of the vehicle antenna device of the present invention, the first conductive film may be arranged in contact with the second main surface, and the second conductive film may be sandwiched between the first intermediate film and the second intermediate film.

[0016] In one embodiment of the vehicle antenna device of the present invention, the first conductive film may be a conductor for reflecting heat rays, the second conductive film may be a light-controlling film including a conductor, and the sheet resistance value of the first conductive film may be lower than the sheet resistance value of the second conductive film.

[0017] In a vehicle antenna device according to one embodiment of the present invention, the conductive film further includes a third conductive film, and the first conductive film, the second conductive film, and the third conductive film are arranged at three positions among a position on the second main surface, a position between the first intermediate film and the second intermediate film, a position on the third main surface, and a position on the fourth main surface, and are arranged in order from closest to the first dielectric substrate, and the third conductive film may have a third hole region arranged so as to overlap with the first hole region in a planar view of the first dielectric substrate.

[0018] In a vehicle antenna device according to one embodiment of the present invention, the first conductive film may be arranged in contact with the second main surface, the second conductive film may be sandwiched between the first intermediate film and the second intermediate film, and the third conductive film may be arranged in contact with the fourth main surface.

[0019] In one embodiment of the vehicle antenna device of the present invention, the first conductive film may be a conductive film for reflecting heat rays, the second conductive film may be a light control film including a conductor, and the third conductive film may be a conductive film for low radiation.

[0020] In the vehicle antenna device according to one aspect of the present invention, the ground electrode may be formed in a loop shape when viewed from above the dielectric substrate.

[0021] In the vehicle antenna device according to one aspect of the present invention, the width of the loop shape of the ground electrode may be 50 mm or less.

[0022] In one aspect of the present invention, the antenna is capable of receiving signals in at least a frequency band of DAB Band III broadcast waves, and the signal electrode has an area of ​​2300 mm 2 in a plan view of the dielectric substrate. 2 Over 5800mm 2 It may be the following:

[0023] In one aspect of the present invention, the antenna is capable of receiving signals in at least an FM broadcast wave frequency band, and the signal electrode has an area of ​​2000 mm 2 in a plan view of the dielectric substrate. 2 It may be more than that.

[0024] In a vehicle antenna device according to one aspect of the present invention, the antenna is capable of receiving signals in at least a frequency band of terrestrial digital television broadcast waves, and the signal electrode has an area of ​​270 mm 2 in a plan view of the dielectric substrate. 2 More than 3700mm 2 It may be the following:

[0025] In the vehicle antenna device according to one aspect of the present invention, the distance between the signal electrode and the ground electrode in a plan view of the dielectric substrate may be 5 mm or more and 20 mm or less.

[0026] In the vehicle antenna device according to one aspect of the present invention, the signal electrode may have a rectangular shape when viewed from above the dielectric substrate.

[0027] In the vehicle antenna device according to one aspect of the present invention, the signal electrode may have a circular shape when viewed from above the dielectric substrate.

[0028] In the vehicle antenna device according to one aspect of the present invention, the dielectric substrate may be a glass substrate.

[0029] In the vehicle antenna device according to one aspect of the present invention, the dielectric substrate may be attached to a roof of the vehicle in parallel with a horizontal plane of the vehicle.

[0030] In the vehicle antenna device according to one aspect of the present invention, the antenna may be arranged to be surrounded by a cover member that protrudes outward from the first main surface side of the dielectric substrate. [Effects of the Invention]

[0031] According to the aspects of the present invention, the vehicle antenna device can obtain a stable gain with minimal mechanical processing of the glass itself. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a perspective view schematically illustrating an example of a vehicle antenna device according to a first embodiment. [Figure 2] 1 is a cross-sectional view showing an example of a vehicle antenna device according to a first embodiment. [Figure 3A] 1 is a configuration diagram showing an example of a vehicle glass according to a first embodiment in a plan view. [Figure 3B] 1 is a configuration diagram showing an example of a vehicle glass according to a first embodiment in a plan view. [Figure 3C] 1 is a configuration diagram showing an example of a vehicle glass according to a first embodiment in a plan view. [Figure 3D] 1 is an enlarged plan view showing an example of a vehicle glass according to a first embodiment. [Figure 4] 2 is a diagram showing an equivalent circuit of the vehicle antenna device of the first embodiment. FIG. [Figure 5] 5 is a diagram showing an example of a simulation result of the characteristics of the vehicle antenna device of the first embodiment. FIG. [Figure 6] 3 is a diagram showing an example of antenna characteristics relative to the size of a signal electrode of the vehicle antenna device of the first embodiment. FIG. [Figure 7] 4 is a diagram showing an example of antenna characteristics relative to the electrode width of the ground electrode of the vehicle antenna device of the first embodiment. FIG. [Figure 8] 4 is a diagram showing antenna characteristics relative to the electrode distance between a signal electrode and a ground electrode of the vehicle antenna device of the first embodiment. FIG. [Figure 9] FIG. 6 is a cross-sectional view showing an example of a vehicle antenna device according to a second embodiment. [Figure 10A] FIG. 6 is a plan view showing an example of a vehicle glass according to a second embodiment. [Figure 10B] FIG. 6 is a plan view showing an example of a vehicle glass according to a second embodiment. [Figure 10C] FIG. 6 is a plan view showing an example of a vehicle glass according to a second embodiment. [Figure 10D] FIG. 6 is an enlarged plan view showing an example of a vehicle glass according to a second embodiment. [Figure 11] FIG. 10 is a diagram showing an example of antenna characteristics relative to the size of a signal electrode of the vehicle antenna device of the second embodiment. [Figure 12] 10 is a diagram showing antenna characteristics with respect to the inter-electrode distance between a signal electrode and a ground electrode of the vehicle antenna device of the second embodiment. FIG. [Figure 13] FIG. 10 is a cross-sectional view showing an example of a vehicle antenna device according to a third embodiment. [Figure 14] FIG. 10 is a cross-sectional view showing an example of a vehicle antenna device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle antenna device according to an embodiment of the present invention will now be described with reference to the accompanying drawings. In the description of the embodiments, the terms "first main surface side," "second main surface side," "third main surface side," and "fourth main surface side" are used. Each of these terms has a meaning including a position on the surface of the main surface or a position away from the main surface in the space facing the main surface. For example, in the relative positional relationship between an arbitrarily selected component A and the main surface, "component A is disposed on the main surface side" not only means that component A and the main surface are in direct contact with each other, but also means that component A is disposed so as to be spaced apart from the main surface. Furthermore, when the main surface and component A are spaced apart, there may or may not be an intervening object between the main surface and component A.

[0034] [First embodiment] Fig. 1 is a perspective view schematically showing an example of a vehicle antenna device 1 according to a first embodiment. Fig. 2 is a cross-sectional view showing an example of a vehicle antenna device 1 according to the present embodiment. The cross-sectional view shown in Fig. 2 is a cross-sectional view taken along line AB of area AR1 in Fig. 1.

[0035] 1 and 2, the vehicle antenna device 1 is an antenna device that uses a vehicle glass 10. The vehicle antenna device 1 includes the vehicle glass 10, an antenna unit 20, and an amplifier unit 30.

[0036] The vehicle glass 10 is, for example, a roof glass attached to the roof of a vehicle. The vehicle glass 10 is attached to the roof of the vehicle parallel (including approximately parallel) to the horizontal plane of the vehicle. Here, an example of the configuration of the vehicle glass 10 will be described with reference to FIG. 2.

[0037] 2, the vehicle glass 10 is, for example, laminated glass. The vehicle glass 10 includes two glass substrates 11 (11-1, 11-2), an antenna conductor 12, a conductive film 13, an intermediate film 14, a signal electrode 15, and a ground electrode 16.

[0038] The glass substrate 11-1 (an example of a first dielectric substrate) and the glass substrate 11-2 (an example of a second dielectric substrate) are glass substrates for laminated glass that are bonded together with an intermediate film 14. Each of the glass substrate 11-1 and the glass substrate 11-2 is an example of a dielectric substrate. The glass substrate 11-1 may be referred to as a first glass substrate, and the glass substrate 11-2 may be referred to as a second glass substrate.

[0039] The shape of the vehicle glass 10 may be curved or flat (non-curved). Furthermore, the vehicle glass 10 may have a single curved shape, for example, curved in either the vertical or horizontal direction (relative to one side of the frame) when installed in a vehicle, or a complex curved shape, curved in both the vertical and horizontal directions. The single curved shape may be a shape curved in only one arbitrary direction. The complex curved shape may be a shape curved in two or more arbitrary different directions. When the vehicle glass 10 has a curved shape, the minimum radius of curvature of the vehicle glass 10 is preferably 500 mm or more and 100,000 mm or less.

[0040] In this embodiment, the main surface of glass substrate 11-1 facing the outside of the vehicle is a first main surface F1. The main surface of glass substrate 11-1 opposite to first main surface F1 is a second main surface F2. The main surface of glass substrate 11-2 facing glass substrate 11-1 is a third main surface F3. The main surface of glass substrate 11-2 opposite to third main surface F3 is a fourth main surface F4.

[0041] The glass substrate 11-2 is disposed parallel to the second main surface F2 of the glass substrate 11-1 so as to face the second main surface F2. The conductive film 13 and the intermediate film 14 are sandwiched between the glass substrates 11-1 and 11-2. As shown in FIG. 2, the conductive film 13 is disposed so as to contact the second main surface F2, but it may also be disposed so as to contact the third main surface F3. The intermediate film 14 may have a multi-layer laminate configuration. In this case, the conductive film 13 may be disposed so as to be inserted between the multiple intermediate film 14 layers. In this case, the conductive film may be a conductor contained in a light-controlling film that can control the visible light transmittance by applying an AC voltage. The light-controlling film includes a pair of resin substrates, a pair of conductive films 13 such as an ITO (indium tin oxide) film, a transparent conductive polymer, a laminated film of a metal layer and a dielectric layer, silver nanowires, and a silver or copper metal mesh, and a light-controlling layer sandwiched between the pair of conductive films 13. In the light control film, the ITO film is provided on the main surface of the resin substrate. Since the main surfaces of the pair of resin substrates face each other, the pair of ITO films also face each other. The light control layer is a molecular layer of optically anisotropic liquid crystal or the like. In FIG. 2, the conductive film 13 is shown as a single layer for convenience, but in the case of a light control film, it refers to a pair of conductive films. Furthermore, the vehicle glass 10 may have a shielding layer (not shown) that blocks visible light. The shielding layer can be disposed on at least one of the second main surface F2, the third main surface F3, and the fourth main surface F4, and may be disposed only on the fourth main surface F4, for example. The shielding layer will also be described in the second embodiment described later.

[0042] The antenna conductor 12 is an electrode connected to the antenna 21. The antenna conductor 12 is arranged on the first principal surface F1 side. For example, the antenna conductor 12 is formed on the first principal surface F1 side of the glass substrate 11-1 in contact with the glass substrate 11-1 (on the glass substrate 11-1). Here, with reference to Figs. 3A to 3D, a configuration example of the antenna conductor 12 will be described. Figs. 3A to 3D are plan views showing the antenna conductor 12 as viewed from outside the vehicle.

[0043] 3A to 3C are plan views showing an example of the vehicle glass 10 of this embodiment. 3A is a plan view of the vehicle glass 10 as viewed from the vehicle exterior (first main surface F1) side. As shown in FIG. 3A, the antenna conductor 12 is a square electrode disposed in the center of the first main surface F1 of the glass substrate 11-1. That is, the antenna conductor 12 is formed in a rectangular shape (including a substantially rectangular shape) when viewed from above the glass substrate 11-1.

[0044] Returning to the description of FIG. 2, the conductive film 13 may be, for example, a conductive film for reflecting heat rays (heat ray reflective film) or a conductive film for low radiation (Low-E (Low Emissivity) coating) that coats the vehicle glass 10. A typical heat ray reflective film is a metal film, and an example of the metal film is silver (Ag). A low-emissivity film such as a Low-E film ensures heat insulation by suppressing heat transfer due to radiation. The Low-E film may be, for example, a stacked film including a transparent dielectric film, an infrared reflective film, and a transparent dielectric film in this order. A typical transparent dielectric film is a metal oxide or a metal nitride, and a typical metal oxide is zinc oxide or tin oxide. The conductive film 13 is disposed on the second main surface F2 side of the glass substrate 11-1 and has a void region VA therein when viewed from above. The conductive film 13 is, for example, in contact with the second main surface F2 and disposed between the glass substrate 11-1 and the glass substrate 11-2. The air hole region VA is arranged so as not to overlap the antenna conductor 12 and the signal electrode 15 in the thickness direction of the vehicle glass 10.

[0045] 3B, the hole regions VA are arranged as square hole regions in a plan view of the glass substrate 11-1. That is, the hole regions VA are formed in a rectangular shape (including a substantially rectangular shape) in a plan view of the glass substrate 11-1.

[0046] Returning to the explanation of Figure 2, the interlayer film 14 is an adhesive layer such as a transparent polyvinyl butyral (PVB) film or an ethylene-vinyl acetate copolymer (EVA) film. The interlayer film 14 is disposed between the glass substrate 11-1 and the glass substrate 11-2. The interlayer film 14 bonds the glass substrate 11-1, the conductive film 13, and the glass substrate 11-2 together, and a laminated glass is formed by the laminated structure of the glass substrate 11-1, the conductive film 13, the interlayer film 14, and the glass substrate 11-2.

[0047] The signal electrode 15 is arranged to face the second main surface F2 located inside the outer edge of the hole region VA in a plan view of the glass substrate 11-2 (11), and is electrically connected to the antenna conductor 12. The signal electrode 15 is arranged, for example, in contact with the fourth main surface F4 of the glass substrate 11-2. The signal electrode 15 is formed to face the antenna conductor 12. The glass substrate 11-1, the intermediate film 14, and the glass substrate 11-2 are sandwiched between the signal electrode 15 and the antenna conductor 12. In this embodiment, the antenna conductor 12 and the signal electrode 15 are arranged to be electrically connected by capacitive coupling.

[0048] The glass substrate 11-1, the interlayer film 14, and the glass substrate 11-2 have thicknesses of, for example, approximately 2 mm, approximately 1 mm, and approximately 2 mm, respectively. The distance between the antenna conductor 12 and the signal electrode 15 is approximately 5 mm. To achieve capacitive coupling of signals with VHF band frequencies and signals with UHF band frequencies, the dielectric distance between the conductors needs to be less than 30 mm, preferably 20 mm or less, and more preferably 10 mm or less. As described above, the thickness of the vehicle glass 10 is typically approximately 5 mm, so the distance between the antenna conductor 12 and the signal electrode 15 is sufficient for capacitive coupling. As such, if the thickness of the vehicle glass 10, which is laminated glass, is less than 30 mm, capacitive coupling between the antenna conductor 12 and the signal electrode 15 is possible. This allows for the amplifier unit 30 to amplify the signal received by the antenna 21.

[0049] The ground electrode 16 is electrically connected to the conductive film 13 in a plan view of the glass substrate 11-2(11). The ground electrode 16 is arranged so as to be electrically connected to the conductive film 13 by capacitive coupling. In other words, the ground electrode 16 is arranged at a position overlapping the conductive film 13 in a plan view of the glass substrate 11-2(11).

[0050] 3C is a plan view of the vehicle glass 10 as viewed from the vehicle interior side (the fourth main surface F4 side). As shown in FIG. 3C, the signal electrode 15 is formed in a rectangular shape (including a substantially rectangular shape) in the plan view of the glass substrate 11-2 (11). Here, the signal electrode 15 is disposed on the fourth main surface F4 side and is formed in a square shape. The ground electrode 16 is formed in a square loop shape when viewed from above on the glass substrate 11-2 (11). That is, the outer and inner edges of the ground electrode 16 are square. The loop shape may be a closed loop that is connected all the way around, or a shape with one or more notches. When the ground electrode 16 has a notch, when the length of one circumference of the closed loop is standardized as "100," the length of the notch portion may be, for example, 40 or less, 30 or less, or 20 or less. Furthermore, the length of the notch portion based on the above standardization may be, for example, 1 or more, 2 or more, or 5 or more.

[0051] FIG. 3D is an enlarged plan view showing a portion indicated by the symbol Q in FIG. 3C, and shows the signal electrode 15 and the ground electrode 16 in FIG. 3C. In FIG. 3D , the length of one side of the signal electrode 15 is (Wo×2). The distance between the ground electrodes 16 and the signal electrode 15 is the electrode distance Sp. The width of the ground electrode 16 is the electrode width Wg. The length of one side of a square representing the periphery (outer edge) of the ground electrode 16 is ((Wo+Sp+Wg)×2). That is, the signal electrode 15 and the ground electrode 16 are formed on the fourth main surface F4 side of the glass substrate 11-2 so that the signal electrode 15 and the ground electrode 16 are spaced apart from each other by the electrode distance Sp and so that the ground electrode 16 has the electrode width Wg. The width of the loop shape of the ground electrode 16 (electrode width Wg) is, for example, 50 mm (millimeters) or less. Here, the electrode width Wg of the loop shape is the width in the direction along the side of the signal electrode 15. The electrode distance Sp is the distance between the ground electrode 16 and the signal electrode 15 in the direction along the side of the signal electrode 15.

[0052] Returning to the explanation of Fig. 2, the antenna unit 20 includes an antenna 21 and an antenna cover 22. The antenna 21 may be, for example, an antenna for receiving the frequency band of FM broadcast waves, an antenna for receiving the frequency band of DAB (Digital Audio Broadcast) broadcast waves, an antenna for receiving the frequency band of terrestrial digital television broadcast waves, an antenna for receiving GNSS (Global Navigation Satellite System) in the 1.2 GHz or 1.6 GHz band, or an antenna for receiving SDARS (Satellite Digital Audio Radio Service) in the 2.3 GHz band. Here, the frequency band of FM broadcast waves (hereinafter referred to as the "FM band") is 76 MHz (megahertz) to 108 MHz, and the frequency band of DAB Band III broadcast waves (hereinafter referred to as the "DAB band") is 174 MHz to 240 MHz. Furthermore, the frequency band of terrestrial digital television broadcast waves (hereinafter referred to as the "DTV band") is 470 MHz to 710 MHz. The antenna 21 may be capable of receiving a plurality of frequency bands among the frequency band of FM broadcast waves, the frequency band of DAB broadcast waves, the frequency band of terrestrial digital television broadcast waves, the frequency band of GNSS, and the frequency band of SDARS.

[0053] The antenna 21 is disposed on the exterior side of the vehicle glass 10 and is connected to the antenna conductor 12 . The antenna cover 22 (cover member) is a protruding cover that is placed on the roof of the vehicle. The antenna cover 22 houses the antenna 21 therein. The antenna cover 22 is, for example, a shark fin antenna cover.

[0054] The amplifier unit 30 amplifies the signal received by the antenna 21 and outputs the amplified signal to, for example, a receiver. An input terminal of the amplifier unit 30 is connected to the signal electrode 15, and a ground terminal of the amplifier unit 30 is connected to the ground electrode 16.

[0055] Next, with reference to FIG. 4, an equivalent circuit of the vehicle antenna device 1 of this embodiment shown in FIG. 2 will be described. FIG. 4 is a diagram showing an equivalent circuit of the vehicle antenna device 1 of this embodiment.

[0056] 4, in the vehicle antenna device 1 of this embodiment, the conductive film 13 functions as an antenna ground. The conductive film 13 is connected to the ground of the amplifier unit 30 and the signal ground of the output signal via a capacitor C1. The capacitor C1 is an electrostatic capacitance formed by the conductive film 13 and the ground electrode 16. The capacitor C1 electrically connects the conductive film 13 and the ground electrode 16 (ground) by capacitive coupling.

[0057] The antenna 21 is connected to an input signal line of the amplifier section 30 via a capacitor C2. The capacitor C2 is an electrostatic capacitance formed by the antenna conductor 12 to which the antenna 21 is connected and the signal electrode 15. The capacitor C2 electrically connects the antenna conductor 12 and the signal electrode 15 by capacitive coupling.

[0058] The signal received by the antenna 21 is input as an input signal to the amplifier unit 30 through the capacitive coupling of the capacitor C2, amplified by the amplifier unit 30, and output to a receiving device (not shown) via the coaxial cable CB. That is, the amplifier unit 30 amplifies the received signal of the antenna 21 based on the power supply power supplied from the power line L1, and outputs the amplified received signal to a receiving device (not shown) via the coaxial cable CB. Note that in Fig. 4, the vehicle antenna device 1 may have a transmission line that connects the signal electrode 15 and the ground electrode 16 to transmit the signal to the amplifier unit 30. The transmission line may be a stripline, a microstripline, a coplanar waveguide, a slotline, or the like.

[0059] Next, the antenna characteristics of the vehicle antenna device 1 of this embodiment will be described with reference to FIGS. FIG. 5 is a diagram showing an example of a simulation result of the characteristics of the vehicle antenna device 1 of this embodiment. The example shown in Fig. 5 shows the results of a simulation of the range in which the S parameter S11 is -10 dB (decibels) or less in the FM, DAB, and DTV frequency bands. Fig. 5 shows the results of a simulation in which the length of one side (Wo × 2) of the signal electrode 15, the electrode spacing Sp, and the electrode width Wg of the ground electrode 16 shown in Fig. 3D are changed.

[0060] 5, the antenna length indicates the length of the antenna element of the antenna 21. For the FM band, the antenna length is 850 mm, for the DAB band, the antenna length is 380 mm, and for the DTV band, the antenna length is 150 mm.

[0061] As shown in FIG. 5, when the antenna 21 can receive the FM band, the area S of the signal electrode 15 is 2000 mm 2 (square millimeters) or more, and the electrode width Wg of the ground electrode 16 is preferably 17 mm or more. In this case, the electrode spacing Sp is preferably 5 mm or more, and the sheet resistance of the conductive film 13 is preferably 50 Ω / □ (ohms / square) or less.

[0062] Furthermore, when the antenna 21 is capable of receiving the DAB band, the area S of the signal electrode 15 is 2300 mm 2 Over 5800mm 2 Preferably, the electrode width Wg of the ground electrode 16 is 5 mm or more. In this case, the electrode spacing Sp is preferably 5 mm or more and 20 mm or less, and the sheet resistance of the conductive film 13 is preferably 12 Ω / □ or less.

[0063] Furthermore, when the antenna 21 is capable of receiving the DTV band, the area S of the signal electrode 15 is 270 mm 2 More than 3700mm 2 Preferably, the electrode width Wg of the ground electrode 16 is 1 mm or more. In this case, the electrode spacing Sp is preferably 7 mm or more and 17 mm or less. The sheet resistance of the conductive film 13 is preferably 320 Ω / □ or less.

[0064] Furthermore, considering the DAB, FM, and DTV bands as a whole, based on the results of FIG. 5, the electrode spacing Sp is preferably, for example, not less than (0.0064×f+4.12) and not more than (−0.0126×f+22.92). Here, “f” is the frequency of the radio waves received by the antenna 21. The unit of radio wave frequency is MHz (megahertz). Furthermore, the electrode width Wg is preferably, for example, not more than 50 mm. Furthermore, the sheet resistance of the conductive film 13 is preferably not more than 320 Ω / □.

[0065] FIG. 6 is a diagram showing an example of antenna characteristics relative to the size of the signal electrode 15 of the vehicle antenna device 1 of this embodiment.

[0066] In Fig. 6, the vertical axis represents the area S of the signal electrode 15, and the horizontal axis represents frequency. Waveform W1 represents the upper limit of the area S at which the S parameter S11 is -10 dB or less. Waveform W2 represents the lower limit of the area S at which the S parameter S11 is -10 dB or less. Range R1 represents the range of the area S at which the S parameter S11 is -10 dB or less. In this case, the electrode width Wg of the ground electrode 16 is set to the lower limit of Fig. 7, and the electrode spacing Sp between the signal electrode 15 and the ground electrode 16 is set to the lower limit of Fig. 8. In the vehicle antenna device 1, sufficient antenna gain can be obtained by setting the area S of the signal electrode 15 to a value within the range R1 in Figure 6 for the frequency bands (FM band, DAB band, DTV band) received by the antenna 21.

[0067] FIG. 7 is a diagram showing an example of antenna characteristics relative to the electrode width Wg of the ground electrode 16 of the vehicle antenna device 1 of this embodiment.

[0068] 7, the vertical axis represents the electrode width Wg of the ground electrode 16, and the horizontal axis represents frequency. Waveform W3 represents the lower limit of the electrode width Wg at which the S parameter S11 is −10 dB or less. The area S of the signal electrode 15 is set to the lower limit shown in FIG. 6, and the electrode spacing Sp between the signal electrode 15 and the ground electrode 16 is set to the lower limit shown in FIG. 8. In the vehicle antenna device 1, sufficient antenna gain can be obtained by setting the electrode width Wg of the ground electrode 16 to be equal to or greater than the value of the waveform W3 for the frequency bands (FM band, DAB band, DTV band) received by the antenna 21.

[0069] FIG. 8 is a diagram showing an example of antenna characteristics with respect to the electrode spacing Sp between the signal electrode 15 and the ground electrode 16 of the vehicle antenna device 1 of this embodiment.

[0070] In Fig. 8, the vertical axis represents the electrode spacing Sp between the signal electrode 15 and the ground electrode 16, and the horizontal axis represents frequency. Waveform W4 represents the upper limit of the electrode spacing Sp at which the S parameter S11 is -10 dB or less. Waveform W5 represents the lower limit of the electrode spacing Sp at which the S parameter S11 is -10 dB or less. Range R2 represents the range of the electrode spacing Sp at which the S parameter S11 is -10 dB or less. Here, the area S of the signal electrode 15 is set to the lower limit of Fig. 6, and the electrode width Wg of the ground electrode 16 is set to the lower limit of Fig. 7. In the vehicle antenna device 1, sufficient antenna gain can be obtained by setting the electrode spacing Sp between the signal electrode 15 and the ground electrode 16 to a value within the range R2 in Figure 8 for the frequency bands (FM band, DAB band, DTV band) received by the antenna 21.

[0071] As described above, the vehicle antenna device 1 of this embodiment includes a glass substrate 11 (dielectric substrate), an antenna 21, an antenna conductor 12, a conductive film 13, a signal electrode 15, and a ground electrode 16. The antenna 21 is disposed on the first main surface F1 side (first main surface side) of the glass substrate 11-1(11). The antenna conductor 12 is connected to the antenna 21 and disposed on the first main surface F1 side. The conductive film 13 is disposed on the second main surface F2 side (second main surface side) of the glass substrate 11-1(11), opposite the first main surface F1 side, and has an air hole region VA therein when viewed from above the glass substrate 11-1(11). The signal electrode 15 is disposed to face the second main surface F2, which is located inside the outer edge of the air hole region VA when viewed from above the glass substrate 11-1(11), and is electrically connected to the antenna conductor. The ground electrode 16 is electrically connected to the conductive film 13 in a plan view of the glass substrate 11.

[0072] As a result, in the vehicle antenna device 1 of this embodiment, the conductive film 13 and the ground electrode 16 are electrically connected by capacitive coupling, and the conductive film 13 functions as an antenna ground. Therefore, in the vehicle antenna device 1 of this embodiment, a large area can be secured as the antenna ground by the conductive film 13, and sufficient antenna gain can be obtained without mechanical processing such as drilling holes in the glass itself.

[0073] The conductive film 13 is a coating film on the vehicle glass 10, such as a heat ray reflecting conductive film and a low-emission conductive film (Low-E coating). Therefore, in the vehicle antenna device 1, these coating films are used as the antenna ground, thereby ensuring a large-area antenna ground. Furthermore, the vehicle antenna device 1 of this embodiment does not require a separate antenna ground.

[0074] In this embodiment, the antenna conductor 12 and the signal electrode 15 are electrically connected by capacitive coupling. As a result, in the vehicle antenna device 1 of this embodiment, the received signal of the antenna 21 can be extracted from the signal electrode 15 without drilling holes in the glass substrate 11, and the antenna 21 can be installed at any location on the vehicle glass 10.

[0075] In this embodiment, the glass substrate 11-1 (dielectric substrate) is the first dielectric substrate. The vehicle antenna device 1 includes a glass substrate 11-2 and an intermediate film 14. The intermediate film 14 is disposed between the glass substrates 11-1 and 11-2. The glass substrate 11-2 is disposed parallel to the second main surface F2 of the glass substrate 11-1 so as to face the second main surface F2 of the glass substrate 11-1. The glass substrate 11-2 has a third main surface F3 facing the glass substrate 11-1 and a fourth main surface F4 opposite the third main surface F3 side (third main surface side). The conductive film 13 is disposed between the glass substrates 11-1 and 11-2. The conductive film 13 is disposed, for example, in contact with the second main surface F2. The signal electrode 15 and the ground electrode 16 are disposed on the fourth main surface F4 side (fourth main surface side). The signal electrode 15 has a substantially rectangular shape when viewed from above on the glass substrate 11-2.

[0076] In this embodiment, the antenna 21 can receive at least a DAB band signal. The signal electrode 15 has an area S of 2300 mm2 in a plan view of the glass substrate 11. 2 Over 5800mm 2 The following is the result. As a result, in the vehicle antenna device 1 of this embodiment, sufficient antenna gain can be obtained when receiving a signal in the DAB band.

[0077] In this embodiment, the antenna 21 can receive at least FM band signals. The signal electrode 15 has an area S of 2000 mm2 in a plan view of the glass substrate 11. 2 As a result, in the vehicle antenna device 1 of this embodiment, sufficient antenna gain can be obtained when receiving signals in the FM band.

[0078] In this embodiment, the antenna 21 can receive at least a DTV band signal. The signal electrode 15 has an area of ​​270 mm 2 in a plan view of the glass substrate 11. 2 More than 3700mm 2 The following is the result. As a result, in the vehicle antenna device 1 of this embodiment, sufficient antenna gain can be obtained when receiving signals in the DTV band.

[0079] In this embodiment, the distance between the signal electrode 15 and the ground electrode 16 (electrode distance Sp) in plan view of the glass substrate 11-2 (11) is 5 mm or more and 20 mm or less. As a result, in the vehicle antenna device 1 of this embodiment, a sufficient antenna gain can be obtained, as shown in FIGS.

[0080] In this embodiment, the glass substrate 11 is attached to the roof of the vehicle substantially parallel to the horizontal plane of the vehicle. The antenna 21 is surrounded by an antenna cover 22 (cover member) that protrudes outward from the first main surface F1 of the glass substrate 11-1. As a result, in the vehicle antenna device 1 of this embodiment, for example, in the roof glass, sufficient antenna gain can be obtained without mechanically processing the glass substrate 11 itself.

[0081] In the above-described embodiment, the signal electrode 15 has a rectangular (approximately rectangular) shape. However, the signal electrode 15 may have a quadrilateral such as a triangle or trapezoid, a pentagon or more polygon, or a polygon having a portion protruding from one side of the quadrilateral by a width shorter than the side in a plan view. In this case, the electrode width Wg of the ground electrode 16 and the electrode spacing Sp between the signal electrode 15 and the ground electrode 16 can be designed appropriately. Furthermore, in a plan view of the glass substrate 11-1, the shapes (outer edges) of the antenna conductor 12 and the signal electrode 15 may be the same or different. If they have the same shape, it is preferable because it facilitates capacitive coupling between the two.

[0082] [Second embodiment] Next, a vehicle antenna device 1a according to a second embodiment will be described with reference to the drawings. The vehicle antenna device 1a according to this embodiment is a modified example of the above-described embodiment. In this embodiment, a case will be described in which the signal electrode 15a of the vehicle glass 10a has a circular shape in a plan view of the vehicle glass 10a. Note that in this embodiment, the glass substrate 11 will be described as a single sheet of glass, but it may also be laminated glass. In the case of laminated glass, the conductive film 13a, which will be described later, may be disposed on the fourth main surface F4.

[0083] FIG. 9 is a cross-sectional view showing an example of a vehicle antenna device 1a according to the second embodiment. The perspective view showing the vehicle antenna device 1a of this embodiment is the same as that of the first embodiment shown in Fig. 1, and therefore the description thereof will be omitted here. Also, in Fig. 9, the configurations of the antenna cover 22 and the amplifier section 30 are the same as those of the first embodiment shown in Fig. 2, and therefore are not shown here.

[0084] As shown in FIG. 9, the vehicle antenna device 1a includes a vehicle glass 10a. The vehicle glass 10a is, for example, a single sheet of glass. The vehicle antenna device 1a includes a glass substrate 11, an antenna conductor 12a, a conductive film 13a, a signal electrode 15a, a ground electrode 16a, and a shielding layer 17 that blocks visible light. The shielding layer 17 is an opaque colored ceramic layer. The color of the shielding layer 17 can be selected arbitrarily, but is preferably a dark color such as black, brown, gray, or dark blue, or white, and more preferably black.

[0085] The glass substrate 11 is a single sheet of glass, and is an example of a dielectric substrate. In this embodiment, the main surface of the glass substrate 11 facing the outside of the vehicle is a first main surface F1. The main surface on the opposite side to the first main surface F1 is a second main surface F2.

[0086] The antenna conductor 12a is an electrode connected to the antenna 21. The antenna conductor 12a is arranged on the first principal surface F1 side. The antenna conductor 12a is formed, for example, on the first principal surface F1 side of the glass substrate 11-1 in contact with the glass substrate 11 (on the glass substrate 11). Here, with reference to Figs. 10A to 10D, a configuration example of the antenna conductor 12a will be described. Figs. 10A to 10D are plan views showing the antenna conductor 12a as viewed from outside the vehicle.

[0087] 10A to 10C are plan views showing an example of a vehicle glass 10a according to this embodiment, where Fig. 10A is a plan view of the vehicle glass 10a as seen from the vehicle exterior side (first main surface F1 side). 10A, the antenna conductor 12a is a circular electrode disposed in the central portion of the first main surface F1 of the glass substrate 11. That is, the antenna conductor 12a is formed in a circular shape (including a substantially circular shape) when the glass substrate 11 is seen in a plan view.

[0088] Returning to the description of FIG. 9, the conductive film 13a may be, for example, a low-emission conductive film (Low-E coat) that coats the vehicle glass 10a. The conductive film 13a is disposed on the second main surface F2 side of the glass substrate 11, and has an air hole region VA therein when viewed from above the glass substrate 11. The conductive film 13a is disposed on the glass substrate 11, for example, in contact with the second main surface F2. The air hole region VA is also disposed so as not to overlap the antenna conductor 12a and the signal electrode 15a in the thickness direction of the vehicle glass 10a.

[0089] 10B, the hole regions VA are arranged as circular hole regions in a plan view of the glass substrate 11. That is, the hole regions VA are formed in a circular shape (including a substantially circular shape) in a plan view of the glass substrate 11.

[0090] Returning to the description of FIG. 9 again, the signal electrode 15a is arranged to face the second main surface F2 located inside the outer edge of the hole region VA in a plan view of the glass substrate 11, and is electrically connected to the antenna conductor 12a. The signal electrode 15a is arranged, for example, in contact with the second main surface F2 of the glass substrate 11. The signal electrode 15a is formed to face the antenna conductor 12a. The glass substrate 11 is sandwiched between the signal electrode 15a and the antenna conductor 12a. In this embodiment, the antenna conductor 12a and the signal electrode 15a are arranged to be electrically connected by capacitive coupling.

[0091] The shielding layer 17 is disposed between the conductive film 13a and the ground electrode 16a. In FIG. 9, the shielding layer 17 has a void region VA similar to that of the conductive film 13a, but the presence or absence of the void region VA can be selected arbitrarily, and the shielding layer 17 may be a layer without the void region VA. In other words, the shielding layer 17 is a continuous layer without voids. The shielding layer 17 may be formed in a so-called "solid" state. In this case, the shielding layer 17 may be formed on the second main surface F2 of the glass substrate 11. The ground electrode 16a is electrically connected to the conductive film 13a in a plan view of the glass substrate 11. The ground electrode 16a is arranged so as to be electrically connected to the conductive film 13a by capacitive coupling. That is, the ground electrode 16a is arranged at a position overlapping the conductive film 13a in a plan view of the glass substrate 11.

[0092] FIG. 10C is a plan view of the vehicle glass 10a as viewed from the vehicle interior (second main surface F2) side. 10C, the signal electrode 15a is formed in a circular shape (including a substantially circular shape) in a plan view of the glass substrate 11. Here, the signal electrode 15a is disposed on the second main surface F2 side and has a circular shape. The ground electrode 16a is formed in a circular loop shape when viewed from above on the glass substrate 11. That is, the outer and inner edges of the ground electrode 16a are circular. The loop shape may be a closed loop that is connected all the way around, or may have one or more notches. If the ground electrode 16 has a notch, the length of the notch can be within the range described in the first embodiment.

[0093] FIG. 10D is an enlarged plan view showing the portion indicated by the symbol R in FIG. 10C, and shows the signal electrode 15a and the ground electrode 16a in FIG. 10C. In FIG. 10D, the distance between the ground electrode 16a and the signal electrode 15a is the electrode distance Sp. The width of the ground electrode 16a is the electrode width Wg. The radius of the circle representing the outer periphery of the ground electrode 16a is the radius Re. That is, the signal electrode 15a and the ground electrode 16a are formed on the second main surface F2 side of the glass substrate 11 so that the signal electrode 15a and the ground electrode 16a are spaced apart from each other by the electrode distance Sp and so that the ground electrode 16a has the electrode width Wg. The width of the loop shape of the ground electrode 16a (electrode width Wg) is, for example, 50 mm or less. Here, the electrode width Wg of the loop shape is the width in the radial direction of the signal electrode 15a. The electrode distance Sp is the distance between the ground electrode 16a and the signal electrode 15a in the radial direction of the signal electrode 15a.

[0094] The equivalent circuit of the vehicle antenna device 1a of this embodiment is the same as that of the first embodiment shown in FIG. The capacitor C1 in this embodiment is an electrostatic capacitance formed by the conductive film 13a and the ground electrode 16a. The capacitor C1 electrically connects the conductive film 13a and the ground electrode 16a (ground) through capacitive coupling. In this embodiment, the arrangement of the shielding layer 17 is arbitrarily selected. Therefore, the equivalent circuit in the case where the vehicle antenna device 1a does not have the shielding layer 17 corresponds to the equivalent circuit in FIG. 4 without the capacitor C1.

[0095] The capacitor C2 in this embodiment is an electrostatic capacitance formed by the antenna conductor 12a connected to the antenna 21 and the signal electrode 15a. The capacitor C2 electrically connects the antenna conductor 12a and the signal electrode 15a by capacitive coupling.

[0096] Next, the antenna characteristics of the vehicle antenna device 1a of this embodiment will be described with reference to Fig. 11 and Fig. 12. The antenna characteristics shown in Fig. 11 and Fig. 12 are simulation results when a Low-E coating is used for the conductive film 13a. The simulation was performed without providing the shielding layer 17. FIG. 11 is a diagram showing an example of antenna characteristics relative to the size of the signal electrode 15a of the vehicle antenna device 1a of this embodiment.

[0097] 11, the vertical axis represents the area S of the signal electrode 15a, and the horizontal axis represents frequency. Waveform W6 represents the upper limit of area S at which the S-parameter S11 is −10 dB or less. Waveform W7 represents the lower limit of area S at which the S-parameter S11 is −10 dB or less. Range R3 represents the range of area S at which the S-parameter S11 is −10 dB or less. In the vehicle antenna device 1a, sufficient antenna gain can be obtained by setting the area S of the signal electrode 15a to a value within the range R3 in Figure 11 for the frequency bands (FM band, DAB band, DTV band) received by the antenna 21.

[0098] FIG. 12 is a diagram showing an example of antenna characteristics with respect to the electrode spacing Sp between the signal electrode 15a and the ground electrode 16a of the vehicle antenna device 1a of this embodiment.

[0099] 12, the vertical axis represents the electrode spacing Sp between the signal electrode 15a and the ground electrode 16a, and the horizontal axis represents frequency. Waveform W8 represents the upper limit of the electrode spacing Sp at which the S-parameter S11 is −10 dB or less. Waveform W9 represents the lower limit of the electrode spacing Sp at which the S-parameter S11 is −10 dB or less. Range R4 represents the range of the electrode spacing Sp at which the S-parameter S11 is −10 dB or less. In the vehicle antenna device 1a, sufficient antenna gain can be obtained by setting the electrode spacing Sp between the signal electrode 15a and the ground electrode 16a to a value within the range R4 in Figure 12 for the frequency bands (FM band, DAB band, DTV band) received by the antenna 21.

[0100] The electrode width Wg of the ground electrode 16a of the vehicle antenna device 1a of this embodiment only needs to be wide enough to connect the ground electrode 16a to the amplifier section 30. In other words, if the thickness of the shielding layer 17 is approximately 5 μm to 25 μm, the conductive film 13a and the ground electrode 16a are capacitively coupled via the shielding layer 17 with a very high coupling capacitance (capacitor C1). Therefore, the electrode width Wg only needs to be wide enough to connect the ground electrode 16a to the amplifier section 30. Furthermore, similarly, even if the vehicle antenna device 1a of this embodiment does not have the shielding layer 17, the electrode width Wg only needs to be wide enough to connect the ground electrode 16a to the amplifier section 30. In this case, the electrode width Wg may be, for example, 1 mm or more.

[0101] As described above, the vehicle antenna device 1a of this embodiment includes a glass substrate 11 (dielectric substrate), an antenna 21, an antenna conductor 12a, a conductive film 13a, a signal electrode 15a, and a ground electrode 16a. The antenna conductor 12a is connected to the antenna 21 and is disposed on the first principal surface F1 side of the glass substrate 11. The conductive film 13a is disposed on the second principal surface F2 side of the glass substrate 11, opposite the first principal surface F1 side, and has a hole region VA therein when viewed from above. The signal electrode 15a is disposed on the second principal surface F2 side of the glass substrate 11, located inside the outer edge of the hole region VA when viewed from above, and is electrically connected to the antenna conductor 12a. The ground electrode 16a is electrically connected to the conductive film 13a when viewed from above. The signal electrode 15a has a substantially circular shape when viewed from above.

[0102] As a result, the vehicle antenna device 1a of this embodiment has the same effects as the vehicle antenna device 1 of the first embodiment described above, and sufficient antenna gain can be obtained with minimal mechanical processing of the glass itself. Although the signal electrode 15a is generally circular, it may be elliptical or have an outer edge with any curved shape. In this case, the electrode width Wg of the ground electrode 16a and the electrode spacing Sp between the signal electrode 15a and the ground electrode 16a can be designed appropriately.

[0103] [Third embodiment] Next, a vehicle antenna device 1b according to a third embodiment will be described with reference to the drawings. The vehicle antenna device 1b according to this embodiment is a modified example of the above-described embodiment. In this embodiment, a case where the vehicle glass 10b is a laminated glass and includes a plurality of conductive films 13 will be described.

[0104] FIG. 13 is a cross-sectional view showing an example of a vehicle antenna device 1b according to the third embodiment. The perspective view showing the vehicle antenna device 1b of this embodiment is the same as that of the first embodiment shown in Fig. 1, and therefore the description thereof will be omitted here. In Fig. 13, the configurations of the antenna cover 22 and the amplifier section 30 are the same as those of the first embodiment shown in Fig. 2, and therefore are not shown here.

[0105] 13, the vehicle antenna device 1b includes a vehicle glass 10b. The vehicle glass 10b is, for example, laminated glass. The vehicle antenna device 1b includes two glass substrates 11 (11-1, 11-2), an antenna conductor 12, three conductive films 13a (13a-1, 13a-2, 13a-3), two intermediate films 14 (14-1, 14-2), a signal electrode 15, and a ground electrode 16. In FIG. 13, the same components as those in the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

[0106] The conductive film 13a of this embodiment includes a conductive film 13a-1 (first conductive film), a conductive film 13a-2 (second conductive film), and a conductive film 13a-3 (third conductive film). The conductive film 13a-1 is, for example, a conductive film for reflecting heat rays (heat ray reflecting film). The conductive film 13a-1 is disposed in contact with the second main surface F2 of the glass substrate 11-1. The sheet resistance of the conductive film 13a-1 is, for example, lower than the sheet resistance of the conductive film 13a-2.

[0107] The conductive film 13a-2 is, for example, a light-controlling film including a conductor. The light-controlling film is a light-controlling film whose light transmittance can be electrically changed. The light-controlling film includes, for example, a transparent conductive film such as ITO. In FIG. 13, the conductive film 13a-2 is shown as a single layer for convenience, but in the case of a light-controlling film, it refers to a pair of conductive films. The conductive film 13a-2 is sandwiched between the intermediate film 14-1 and the intermediate film 14-2. The conductive film 13a-2 has a second air hole region VA2 that is arranged to overlap with the first air hole region VA1, which is the air hole region VA of the conductive film 13a-1, in a planar view of the glass substrate 11-1. Note that, in a planar view of the glass substrate 11-1, it is preferable that the outer edges of the first air hole region VA1 and the second air hole region VA2 coincide with each other, although some misalignment is acceptable.

[0108] The interlayer 14 of this embodiment includes an interlayer 14-1 (first interlayer) and an interlayer 14-2 (second interlayer). The interlayer 14-1 and the interlayer 14-2 are, for example, PVB films or EVA films, but it is preferable that the interlayer 14-1 and the interlayer 14-2 be made of the same material. The conductive film 13a-3 is, for example, a low-emissivity conductive film (Low-E coating). The conductive film 13a-3 is disposed in contact with the fourth main surface F4 of the glass substrate 11-2. The conductive film 13a-3 also has a third hole region VA3 that is disposed to overlap the first hole region VA1 in a plan view of the glass substrate 11-1. In a plan view of the glass substrate 11-1, it is preferable that the outer edges of the first hole region VA1 and the third hole region VA3 coincide with each other, although some misalignment is acceptable.

[0109] The ground electrode 16 of this embodiment is disposed in contact with the conductive film 13a-3. As in the second embodiment, a shielding layer 17 may be disposed between the conductive film 13a-3 and the ground electrode 16.

[0110] As described above, in this embodiment, the conductive film 13a includes a conductive film 13a-1 (first conductive film), a conductive film 13a-2 (second conductive film), and a conductive film 13a-3 (third conductive film). The intermediate film 14 includes an intermediate film 14-1 (first intermediate film) and an intermediate film 14-2 (second intermediate film). The conductive film 13a-2 is sandwiched between the intermediate film 14-1 and the intermediate film 14-2. The conductive films 13a-1, 13a-2, and 13a-3 may be arranged at three positions among a position on the second main surface F2, a position between the intermediate film 14-1 and the intermediate film 14-2, a position on the third main surface F3, and a position on the fourth main surface F4, and may be arranged in order from the position closest to the glass substrate 11-1. The conductive film 13a-3 has a third hole region VA3 that is arranged so as to overlap the first hole region VA1 in a plan view of the glass substrate 11-1.

[0111] As a result, in the vehicle antenna device 1b of this embodiment, at least one of the conductive films 13a-1, 13a-2, and 13a-3 functions as an antenna ground. Therefore, the vehicle antenna device 1b of this embodiment has the same effects as the first and second embodiments, and sufficient antenna gain can be obtained with minimal mechanical processing of the glass itself.

[0112] In this embodiment, the conductive film 13a-1 is a conductive film for reflecting heat rays (heat ray reflecting film), the conductive film 13a-2 is a light control film including a conductor, and the conductive film 13a-3 is a conductive film for low emissivity (Low-E coating). As a result, in the vehicle antenna device 1b of this embodiment, the vehicle glass 10b is provided with heat ray reflection, light control, and low radiation functions, while the antenna 21 provides sufficient antenna gain.

[0113] In the present embodiment, an example has been described in which the vehicle glass 10b includes three conductive films 13a. In the configuration of the vehicle glass 10b, one conductive film 13a may be sandwiched between the intermediate film 14-1 and the intermediate film 14-2. Furthermore, the conductive film 13a may be disposed in contact with the third main surface F3 or the fourth main surface F4.

[0114] In this embodiment, the vehicle glass 10b may include two conductive films 13a. In this case, the conductive films 13a-1 and 13a-2 may be arranged in two of the following positions: on the second main surface F2, between the intermediate films 14-1 and 14-2, on the third main surface F3, and on the fourth main surface F4, and may be arranged in order from closest to the glass substrate 11-1. In this case, the conductive film 13a-2 has a second hole region VA2 that is arranged to overlap with the first hole region VA1, which is the hole region VA of the conductive film 13a-1, in a plan view of the glass substrate 11-1.

[0115] Furthermore, when the vehicle glass 10b has three conductive films 13a, the conductive films 13a-1, 13a-2, and 13a-3 may be arranged at three positions among a position on the second main surface F2, a position between the intermediate film 14-1 and the intermediate film 14-2, a position on the third main surface F3, and a position on the fourth main surface F4, and may be arranged in order from the position closest to the glass substrate 11-1.

[0116] [Fourth embodiment] Next, a vehicle antenna device 1c according to a fourth embodiment will be described with reference to the drawings. The vehicle antenna device 1c according to this embodiment is a modified example of the above-described embodiment. In this embodiment, the case where the antenna conductor 12b and the signal electrode 15a are directly connected by the connecting conductor 18 will be described.

[0117] FIG. 14 is a cross-sectional view showing an example of a vehicle antenna device 1c according to the fourth embodiment. The cross-sectional view showing the vehicle antenna device 1c of this embodiment is similar to that of the second embodiment shown in Fig. 9, and therefore the description thereof will be omitted here. In Fig. 14, the configurations of the antenna cover 22 and the amplifier section 30 are similar to those of the first embodiment shown in Fig. 2, and therefore are not shown here.

[0118] 14, the vehicle antenna device 1c includes a vehicle glass 10c. The vehicle antenna device 1c includes a glass substrate 11, an antenna conductor 12b, a conductive film 13a, a signal electrode 15a, a ground electrode 16a, a shielding layer 17, and a connecting conductor 18. In FIG. 14, the same components as those in the second embodiment shown in FIG. 9 are denoted by the same reference numerals, and the description thereof will be omitted.

[0119] The connection conductor 18 is a conductor disposed in the through-hole of the glass substrate 11 . In this embodiment, the antenna conductor 12b and the signal electrode 15a are directly connected by a connecting conductor . Other configurations of this embodiment are the same as those of the second embodiment shown in FIG. 9, and therefore description thereof will be omitted here.

[0120] As described above, in this embodiment, the antenna conductor 12b and the signal electrode 15a are directly connected by the connection conductor 18 disposed in the through-hole of the glass substrate 11. As a result, in the vehicle antenna device 1c of this embodiment, similar to the second embodiment, sufficient antenna gain can be obtained with minimal mechanical processing of the glass itself.

[0121] The present invention is not limited to the above-described embodiments, and can be modified within the scope of the present invention. For example, in each of the above embodiments, the antenna unit 20 is a shark fin antenna, but the present invention is not limited to this and may be, for example, a rod antenna.

[0122] Furthermore, in each of the above embodiments, the dielectric substrate is a glass substrate 11, but this is not limited to this, and the dielectric substrate may be a substrate using other dielectrics, such as a plastic substrate (resin substrate).

[0123] In addition, in the above first and third embodiments, examples have been described in which the vehicle glass 10 (10b) does not have a shielding layer 17, but in the first and third embodiments, the shielding layer 17 may also be provided. In addition, in the above second and fourth embodiments, examples have been described in which the vehicle glass 10a (10c) is provided with a shielding layer 17, but in the second and fourth embodiments, the shielding layer 17 may not be provided.

[0124] In addition, in each of the above embodiments, the vehicle antenna device 1 (1a, 1b, 1c) has been described as having one antenna 21 installed on the vehicle glass 10 (10a, 10b, 10c), but this is not limited thereto, and multiple antennas 21 with different frequency bands may be installed. Also, the antenna 21 may be used to receive signals in multiple frequency bands. [Explanation of symbols]

[0125] 1, 1a, 1b, 1c Vehicle antenna device 10, 10a, 10b, 10c Vehicle glass 11, 11-1, 11-2 Glass substrate 12, 12a, 12b Antenna conductor 13, 13a, 13a-1, 13a-2, 13a-3 Conductive film 14, 14-1, 14-2 Interlayer 15, 15a signal electrode 16, 16a ground electrode 17 Shielding layer 18 Connecting conductor 20 Antenna section 21 Antenna 22 Antenna cover 30 Amplifier section C1 and C2 capacitors F1 First main surface F2 Second principal surface F3 Third principal surface F4 4th main surface VA vacancy area VA1 1st vacancy area VA2 2nd vacancy area VA3 3rd hole area

Claims

1. a dielectric substrate; an antenna disposed on a first main surface side of the dielectric substrate; an antenna conductor connected to the antenna and disposed on the first principal surface side; a conductive film disposed on a second main surface side of the dielectric substrate opposite to the first main surface side, the conductive film having a void region therein when viewed from above the dielectric substrate; a signal electrode disposed on the second principal surface, inward from an outer edge of the hole region, in a plan view of the dielectric substrate, and electrically connected to the antenna conductor; a ground electrode electrically connected to the conductive film in a plan view of the dielectric substrate; A vehicle antenna device comprising:

2. The antenna conductor and the signal electrode are electrically connected by capacitive coupling. The vehicle antenna device according to claim 1 .

3. The antenna conductor and the signal electrode are directly connected by a connecting conductor disposed in a through hole of the dielectric substrate. The vehicle antenna device according to claim 1 .

4. the dielectric substrate is a first dielectric substrate, a second dielectric substrate facing the second main surface of the first dielectric substrate and disposed parallel to the second main surface; an intermediate film disposed between the first dielectric substrate and the second dielectric substrate; Equipped with the second dielectric substrate has a third main surface facing the first dielectric substrate and a fourth main surface opposite to the third main surface, the conductive film is disposed between the first dielectric substrate and the second dielectric substrate; The signal electrode and the ground electrode are disposed on the fourth principal surface side. The vehicle antenna device according to claim 1 .

5. The conductive film is disposed in contact with the second main surface. The vehicle antenna device according to claim 1 .

6. The interlayer film includes a first interlayer film and a second interlayer film, The conductive film is sandwiched between the first intermediate film and the second intermediate film.

5. The vehicle antenna device according to claim 4.

7. The conductive film is a light-control film containing a conductor.

7. The vehicle antenna device according to claim 6.

8. The conductive film is disposed in contact with the third main surface or the fourth main surface.

5. The vehicle antenna device according to claim 4.

9. The interlayer film includes a first interlayer film and a second interlayer film, the conductive film includes a first conductive film and a second conductive film, the first conductive film and the second conductive film are arranged at two positions among a position on the second main surface, a position between the first intermediate film and the second intermediate film, a position on the third main surface, and a position on the fourth main surface, and are arranged in order from the position closest to the first dielectric substrate; The second conductive film has a second hole region that is arranged so as to overlap with a first hole region, which is the hole region of the first conductive film, in a plan view of the first dielectric substrate.

5. The vehicle antenna device according to claim 4.

10. the first conductive film is disposed in contact with the second main surface, The second conductive film is sandwiched between the first intermediate film and the second intermediate film.

10. The vehicle antenna device according to claim 9.

11. the first conductive film is a heat ray reflecting conductor, the second conductive film is a light control film including a conductor, The sheet resistance value of the first conductive film is lower than the sheet resistance value of the second conductive film.

10. The vehicle antenna device according to claim 9.

12. the conductive film further includes a third conductive film, the first conductive film, the second conductive film, and the third conductive film are arranged at three positions among a position on the second main surface, a position between the first intermediate film and the second intermediate film, a position on the third main surface, and a position on the fourth main surface, and are arranged in order from the position closest to the first dielectric substrate; The third conductive film has a third hole region that is arranged so as to overlap the first hole region in a plan view of the first dielectric substrate.

10. The vehicle antenna device according to claim 9.

13. the first conductive film is disposed in contact with the second main surface, the second conductive film is sandwiched between the first intermediate film and the second intermediate film, The third conductive film is disposed in contact with the fourth main surface. The vehicle antenna device according to claim 12.

14. the first conductive film is a conductive film for reflecting heat rays, the second conductive film is a light control film including a conductor, The third conductive film is a low-emission conductive film. The vehicle antenna device according to claim 12.

15. The ground electrode is formed in a loop shape when viewed from above the dielectric substrate. The vehicle antenna device according to claim 1 .

16. The width of the loop shape of the ground electrode is 50 mm or less.

16. The vehicle antenna device according to claim 15.

17. The antenna is capable of receiving signals in at least a frequency band of DAB Band III broadcast waves, The signal electrode has an area of ​​2300 mm2 or more and 5800 mm2 or less in a plan view of the dielectric substrate. The vehicle antenna device according to any one of claims 1 to 16.

18. The antenna is capable of receiving signals in at least an FM broadcast wave frequency band, The signal electrode has an area of ​​2000 mm2 or more in a plan view of the dielectric substrate. The vehicle antenna device according to any one of claims 1 to 16.

19. the antenna is capable of receiving signals in at least a frequency band of terrestrial digital television broadcast waves, The signal electrode has an area of ​​270 mm2 or more and 3700 mm2 or less in a plan view of the dielectric substrate. The vehicle antenna device according to any one of claims 1 to 16.

20. The distance between the signal electrode and the ground electrode in a plan view of the dielectric substrate is 5 mm or more and 20 mm or less. The vehicle antenna device according to any one of claims 1 to 16.

21. The signal electrode has a rectangular shape when viewed from above the dielectric substrate. The vehicle antenna device according to any one of claims 1 to 16.

22. The signal electrode has a circular shape when viewed from above the dielectric substrate. The vehicle antenna device according to any one of claims 1 to 16.

23. The dielectric substrate is a glass substrate. The vehicle antenna device according to any one of claims 1 to 16.

24. The dielectric substrate is attached to the roof of the vehicle parallel to the horizontal plane of the vehicle. The vehicle antenna device according to any one of claims 1 to 16.

25. The antenna is disposed surrounded by a cover member that protrudes outward from the first main surface side of the dielectric substrate. The vehicle antenna device according to any one of claims 1 to 16.

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